1. Technical Field
The present invention relates to a liquid ejecting head that has a filter for filtering liquid, and a liquid ejecting apparatus including the liquid ejecting head.
2. Related Art
A liquid ejecting apparatus includes a liquid ejecting head and ejects (discharges) various kinds of liquids from the liquid ejecting head. Examples of the liquid ejecting apparatus include image recording apparatuses such as ink jet printers and ink jet plotters. Such liquid ejecting apparatuses can accurately eject very small amounts of liquid at predetermined positions and have been used in various manufacturing apparatuses. Such applications include, for example, display manufacturing apparatuses for manufacturing color filters for liquid crystal displays, electrode forming apparatuses for forming electrodes for organic electroluminescence (EL) displays and field emission displays (FEDs), and chip manufacturing apparatuses for manufacturing biochips (biochemical chips). A recording head for the image recording apparatuses ejects liquid ink, and a color material ejecting head for display manufacturing apparatuses ejects solutions of individual red (R), green (G), and blue (B) coloring materials. An electrode material ejecting head for the electrode forming apparatus ejects a liquid electrode material, and a bioorganic compound ejecting head for the chip manufacturing apparatus ejects a solution of bioorganic compounds.
These liquid ejecting heads introduce a liquid from a liquid supply source that stores the liquid and drive a drive element such as a piezoelectric element, a heating element, or the like to eject the ink from a nozzle in the form of droplets. Some of the liquid ejecting heads employ a mechanism to filter the introduced liquid to capture foreign matter and bubbles contained in the liquid by using a filter. In a liquid flow path, a portion where the filter is placed has a cross-sectional area that is larger than that of other portions of the flow path, and this portion forms a space (hereinafter, referred to as a filter chamber). In the filter chamber, rib-shaped protrusions may be provided, for example, to increase the flow rate of the liquid flowing toward the filter or to provide a path that enables the liquid to pass through the filter even if bubbles are partly covering the filter (for example, see JP-A-2006-69168).
In order to increase the degree of bubble discharging in a maintenance operation (cleaning operation) for discharging bubbles on the upstream side of a filter by applying a negative pressure to a nozzle surface having a nozzle of a liquid ejecting head or by applying a pressure to a liquid flowing in a flow path, it is preferable that the bubbles cover the entire filter and clog the filter. However, the above-mentioned ribs may prevent the bubbles from sufficiently spreading onto the filter and may cause a reduction in the degree of bubble discharging.